Recently, responding to rising environmental awareness, there is a movement to shift the power source of automobiles from engines using fossil fuel, to motors utilizing electrical energy. Therefore technology of a battery to be used as the power source of motors has rapidly been developing.
An automobile is desired to mount a compact-size and light-weight battery, capable of charging and discharging high power frequently, and excellent in vibration resistance and heat radiation performance. In response to such requirements, a combined battery constructed by connecting a large number of flat-type cells in series, has recently been developed as shown in JP-A-2004-31136.